Need some serious advice. Is it time to go mass air?

[ramjetlx]

I just upgraded my bottom end to a 347 stroker. My car is still a speed density with the stock 19lbs injectors. Problem is that everytime I start the car up it runs really rough until I drive about 10 miles and then the car starts to run okay. I think the computer is going crazy, the car will miss and backfire while driving after starting up, and then it will smooth out after 10 miles. Is it time to switch to mass air? My car is a street car and I like to have no idle or missing problems in the lower rpms. Heres what I have and done:

Set fuel pressure to 50 psi.Have a 190lph pump.
I have a 3000 stall converter, shift kit and 4.10 gears.
MSD 6AL with MSD distributor, coil pack and wires. Plugs gapped to 35 at stock heat range.
1.7 roller rockers with cold air intake.
Removed a/c and smog pump.
Full exhaust upgrade, 1 5/8 equal length shorties, off road h pipe, Super 40s.
Basically everything is bone stock. Compression is 9:2.1 with a 347 stroker.

Theres nothing major here except for the stroker. Ive heard of people running them okay on speed density, but im having some serious lower rpm drivabiltiy issues. Any advice or solutions is greatly appreciated!!

 

[tmoss]

You have a couple of choices I guess. Pay for a dyno tune to see if the FP can be adjusted to suit the needs of the engine or buy some 24#/30# injectors and experiment your self.

 

[Black1987Stang]

I would go mass air, im sure you going to mod more in the future. You can get a reman. comp at advance auto for 100 bucks, a wiring harness for 45 bucks or u could make ur own but i would just buy it pre-made, and you can find a stock maf for prob 50 bucks if not cheaper, and youll need a cone filter too which is cheap.

 

[TC93]

You're running 50# of fuel pressure??? I would back FP down to around 40-42#'s. Gap the plugs back into the stock range. If all you have is the stroker bottom end with stock heads and intake, then there is no need for all that FP.

 

[1988WHTGT]

I've got an A9L computer and a mass air plug for sale.

 

[ForceFed70]

Instead of going to mass air, consider converting to a megasquirt ECU.

It's cheap and will cost you less than $500 total..yet you can keep all of your current hardware and will end up with a fully tunable ECU.

Do a google search for "megasquirt"

 

[ramjetlx]

You're running 50# of fuel pressure??? I would back FP down to around 40-42#'s. Gap the plugs back into the stock range. If all you have is the stroker bottom end with stock heads and intake, then there is no need for all that FP.

Actually, since Im running the MSD 6AL I was told by MSD to gap my plugs at 35-40. Wouldnt I need more fuel because of more air? My motor would ping when I had it at 45psi, thats why I went to 50psi and it doesnt ping anymore.
Maybe I should upgrade to 24lb injectors?

 

[Paul Perreca]

I would go mass air, im sure you going to mod more in the future. You can get a reman. comp at advance auto for 100 bucks, a wiring harness for 45 bucks or u could make ur own but i would just buy it pre-made, and you can find a stock maf for prob 50 bucks if not cheaper, and youll need a cone filter too which is cheap.

my stock maf was 6 bucks, plus 7 shipping on ebay so your running a stroker w/ stock heads and stock cam and stock intake?

 

[Michael Yount]

Lets see -- SD maps designed for 302 cubes of displacement running a 347....hmmm.....

Yeah - it's time for a swap - mass air or the megasquirt system mentioned above. Megasquirt is basically a user-friendly tunable SD system.

 

[tmoss]

If you could get the 347 VE curve close to the VE curve of the 302, the 347 should run basically like the 302 with 21-24# injectors. I wonder if Buddy, Ed or Jay have been asked to cut a cam for such an SD application.

 

[FordGuy88]

I've got an A9L computer and a mass air plug for sale.

He cant use a A9L computer. He has an AOD, he needs the A9P. I got a A9P, a full mass air harness, the maf sensor, and the maf intake tube for $120. So I would just go mass air.

 

[jackchan]

dang that is cheap for a computer, harness, maf sensor, and intake tube!
I wouldnt take less than $175 for all that off one of my parts cars......well I might would take $100 for just the harness!

 

[FordGuy88]

$100 for just the harness. O My God. There are guys selling mass air harnesses on chitown for $50 all day.